What happened
During a flight, the crew found that the airplane required full nose-down trim and continuous forward pressure on the yoke to maintain level flight. Following this flight, a logbook entry was recorded, and a subsequent inspection of the aircraft revealed physical damage caused by contact between the elevator and the rudder.
The investigation
Investigators examined the elevator gust lock mechanism and discovered that only three of the four required elevator stop bumpers were installed. While the mount bolt for the upper right bumper remained in place, the bumper itself was missing. Additionally, the upper left bumper was found to be severely degraded, exhibiting cracking, chipping, crazing, and a longitudinal crack extending its entire length.
Flight Data Recorder (FDR) analysis showed that during the previous flight, as the aircraft taxied onto the departure runway, the gust lock was released. This release resulted in rapid deflection of the control yoke and the elevator control surfaces. At the moment the control yoke returned to its nominal position, a 4-degree separation was noted between the left-hand and right-hand elevator graph lines. This 4-degree separation persisted throughout the rest of the flight, whereas data from prior flights showed that the elevator control surface graph lines were normally superimposed in all modes of flight.
At the time of the taxi event, winds at the departure airport were reported from 300 degrees at 22 knots, with gusts reaching 27 knots.